Thats if you want to spend money in America. I grew up on the border and even worked a short stint in customs. They can be right anal if they think you're actually do anything productive. Could've just been the fine folk in Montana. Tight squinting eyes boring through your soul. Fingers rapping gently over the grip of their pistol. Waiting and watching you as a stillness fills the air, offering you no escape. "You boys ain't look'n at taki'n jobs from good 'merican boys now are ya?"

As someone mentioned, you can 'visit' but I'm not sure how well that'd work overall. Boston is a 5 hour drive from Montreal. If I recall correctly YC has funded outsiders before. I would be very interested to hear how they managed.

I think Y Combinator would be an amazing experience that I wouldn't get anywhere else. I'd be more than willing to give up several months of my life to move to a new country to learn and work with amazing people. The question of the border is the biggest stumbling block in the path.